The orthopedic device is, in particular, a so-called orthosis, i.e. a device which supports a limb that is present. However, in principle, the orthopedic device can also be a so-called prosthesis, which at least partly replaces a limb.
Here, an actuator of an orthopedic device should be understood to mean any means which influences a relative movement between parts of the orthopedic device. This influencing may be passive, such as in the case of e.g. a damper, or else active, such as in the case of e.g. a motor.
If the term “movement pattern” is used in the following, it in particular includes the meaning of a “gait”; however, it is not restricted thereto, even in the case of a lower limb.
In the case of an unchanging movement pattern, for example when walking in a plane or when climbing stairs, which is carried out continuously, it is comparatively easy to set the actuator of an orthopedic device in a manner that fits. However, when the movement pattern changes, there needs to be an adjustment to a different setting of the actuator. This adjustment can be undertaken manually by the user of the orthopedic device or it can be triggered by means of a specific movement of the orthopedic device. However, a precondition for a movement with the orthopedic device that is as unimpeded as possible for the user is that the orthopedic device adapts the actuator or actuators thereof independently to the current movement pattern. To this end, various suggestions have already been proposed.
A leg prosthesis with an artificial knee joint and a method for controlling a leg prosthesis are known from EP 1 058 524 B1. The leg prosthesis includes a thigh part, a below-knee part and a knee joint connecting the two. The knee joint comprises a damping element for controlling the knee joint movement. An apparatus registers the knee angle and a further apparatus registers the force acting on the prosthesis. A controller for controlling the damping element as a function of the registered values for the knee angle and for the force is regulated in accordance with the gait of the wearer of the leg prosthesis. Here, the controller is embodied in such a way that it controls the damping element as a function of control parameters for various gait speeds stored in advance. These parameters are corrected within the scope of regulating the control as a function of the gait. To this end, a control parameter is selected from the stored control parameters as a function of the registered values for the knee angle and for the force. The selected control parameter is then modified to a value as a function of the registered values for the knee angle and for the force, which value equals, or is different from, the previously stored value. This modified control parameter is then stored in place of the selected control parameter. This regulation sets in when established actual step values deviate from predetermined intended step values which are the same for each prosthesis wearer. By way of example, these include a maximum bend angle and a lead-in time, which is the time between an extension limit and touchdown of the heel within a step. In this manner, the control of the damping element is adapted to the respective prosthesis wearer.
EP 1 531 767 B1 has disclosed a control apparatus and a method for controlling a prosthesis comprising an actuator. This includes a method for determining a locomotion portion and a locomotion phase portion in order to be able to control the prosthesis in real time. This method comprises the provision of a plurality of main artificial proprioceptors, the reception of a data signal from each one of the main artificial proprioceptors, the obtainment of a first and a second derivative signal from the data signals, the obtainment of a third derivative signal for at least some of the data signals and the use of a set of first state machines in order to select a state from a multiplicity of possible states for each main artificial proprioceptor with the corresponding data and derivative signals. Furthermore, the locomotion phase portion is generated using the states of the main artificial proprioceptors; and a second state machine is used to select the locomotion portion using results which are assigned to the data signals from a plurality of possible locomotion portions. That is to say, the locomotion portion and the locomotion phase portion, i.e. movement state and phase, are identified in addition to the current values of the main artificial proprioceptors by various derivatives of said values and are linked to specific commands for the actuator of the prosthesis. To this end, the signals from the main proprioceptors or the derivatives thereof are compared to entries in comparison value tables and, to the extent that a correspondence is present, the actuators are actuated by actuation commands linked to these entries in the comparison value tables. Here, the entries in the comparison value tables are fixed, i.e. not adapted to the individual prosthesis wearer.
DE 10 2007 053 389 A1 has disclosed a method for controlling an orthopedic joint of a lower extremity in at least one degree of freedom using an adjustable actuator which, for the purposes of adapting an orthopedic device, which includes top-side connection means to a limb and an orthopedic joint arranged in a hinged manner distally from the connection means, serves walking situations that deviate from walking in the plane. In this known method, a plurality of parameters of the orthopedic device are registered by means of sensors. The registered parameters are compared to criteria which were generated on the basis of a plurality of parameters and/or parameter profiles and which are stored in a computer unit. A criterion suitable on the basis of the established parameters and/or parameter profiles is selected, and movement resistors, scopes of movement, drive forces and/or the profiles thereof are adapted as a function of the selected criterion in order to control extra functions.
DE 10 2008 024 748 A1 has disclosed a knee orthosis and a method for controlling a knee orthosis. The method for controlling the knee orthosis, which includes a thigh structure, a joint apparatus and a below-knee structure comprising a foot part, provides for an effective torque, in particular an ankle element, to be determined within the orthosis and for the resistance of the actuator unit to be modified as a function of the torque. In a complementary manner, the actuator unit can be modified as a function of a knee torque, the knee angle or the spatial orientation of at least one thigh structure or below-knee structure. As a result, it is possible to provide control of the standing and swing phase in the case of patients with paralysis, who can no longer control their leg as desired. The section modulus, which, for example, can be modified by means of a hydraulic actuator, renders it possible to generate a knee torque in such a way that standing phase flexion and alternating downward walking and walking downstairs are made possible. An appropriate support of the movement should be brought about by means of active actuator units.
DE 10 2009 052 887 A1 has disclosed a method for controlling an orthotic or prosthetic joint of a lower extremity. The joint includes a resistance apparatus, to which at least one actuator is assigned, by means of which the bending and/or extension resistance is modified as a function of sensor data. Sensors provide state information during the use of the joint. The sensor data are established by at least one apparatus for registering at least two torques or a torque and a force. The sensor data of at least two variables established thus are linked to one another by a mathematical operation. As a result, at least one auxiliary variable is calculated, on which the control of the bending and/or extension resistance is based.
A method for controlling at least one adjustable actuator of an orthopedic device including connection apparatuses to a lower limb, and a corresponding orthopedic device comprising connection apparatuses to a lower limb, an adjustable actuator, at least two sensors, which continuously register actual values of at least two movement parameters of the orthopedic device, and a control apparatus which analyzes the registered values and sets the actuator using control signals on the basis thereof, which orthopedic device components are known from DE 195 21 464 A1. This relates specifically to the control of the knee brake of a prosthetic knee joint of a thigh prosthesis. Here, a computer controlled braking torque is modified continuously between “free” and “blocked” as a function of the gait movement of the prosthesis wearer and the gait movement is characterized in the form of measurement data by measured EMG values, pressure values measured in the region of the foot, by the respective knee angle and the respective angular speed measured between prosthesis thigh part and below-knee part. For the purposes of improved adaptation of the knee braking control to various natural gaits, the respective gait is established from a number of predetermined gaits, established in advance for the respective prosthesis wearer, by evaluating at least some of the measurement data. Then, a control program assigned to this established gait is selected. A step period, defined as a period of time between two successive heel/floor contacts subdivided into a plurality of phases is set for each control program, the respective endpoint of which is determined by measurement data that is predetermined for this phase and transmitted in each case. Specific brake values which are applied to the knee brake and which possibly change during this phase are assigned to each phase. The respective carried out gait is established by comparing the transmitted measurement data with reference data predetermined for each gait. Here, it is intended to be expedient to establish the reference data from the EMG data measured for each individual gait. Basing the establishment of the respectively carried out gait on EMG data requires the reproducible measurement thereof. However, recording EMG data is not at all possible in the case of some patient groups. Moreover, establishing the gaits by data comparison is complicated and susceptible to errors. The known method and the corresponding thigh prosthesis have therefore not found widespread use in practice.
S. D. Prentice et al.: Simple artificial neuron network models can generate basic muscle activity patterns for human locomotion at different speeds, Exp. Brain Res (1998) 123:474-480 has disclosed the practice of representing muscle activation patterns when walking with the aid of an artificial neural network on the basis of a sine function and a cosine function with a period length equal to the duration of a step.
DE 601 31 377 T2 has disclosed a speed-adapted and patient-adapted control scheme for a knee prosthesis to carry out a method for controlling at least one adjustable actuator of an orthopedic device including connection apparatuses to a lower limb. The control scheme is provided for controlling a standing phase damping of the knee prosthesis worn by a patient. Correlations in respect of sensor data and the standing phase damping are stored in a memory of the knee prosthesis. These correlations are set on the basis of clinical tests of amputees with different body sizes and characterize the knee behavior when the foot prosthesis is in contact with the floor. Sensor information is used in conjunction with these correlations in order to define how the standing phase damping is intended to be modulated when standing, walking or running.
US 2009/0054996 A1 has disclosed a knee prosthesis which includes an adjustable joint movement control unit for automatically controlling the joint. An electronic memory unit stores a target relationship between a kinetic or kinematic movement parameter and the walking speed. The target relationship defines a number of values of the movement parameter, which are respectively connected to a different walking speed. A monitoring system generates monitoring signals that reproduce the walking speed values and values of the movement parameter, as occur at different walking speeds. An adaptation system automatically adapts the joint movement control unit if the monitoring signals show a deviation from the target relationship in order to bring the movement parameter back into the range of a value defined by the target relationship for the respective walking speed.